NFT-Based Digital Identities for Transparent and Trustworthy Smart Water Metering in Smart Cities

Transparent and efficient water management is becoming a necessity for smart cities worldwide. Recently, technological advancements in water system infrastructure are helping address modern challenges for sustainable water management, particularly in densely populated cities experiencing rapid urbanization. Smart water metering (SWM) systems are increasingly deployed because they generate detailed consumption data and enable early identification of system-wide water losses. However, privacy and security risks, including unauthorized ownership, data manipulation, and tampering, can create mistrust between utilities and citizens, especially when combined with issues such as system-wide water loss, unhealthy physical water infrastructure, and billing inaccuracies. This study introduces a conceptual framework that explores how non-fungible tokens (NFTs) might contribute to more transparent and trustworthy SWM operations. In this approach, each meter is assigned a unique NFT-based digital identity, allowing installation records, maintenance logs, ownership status, and usage history to be represented in a structured and traceable way. The framework is compared with existing identity and asset-representation mechanisms, including PKI, DIDs, and non-tokenized blockchain registries. A simple data flow model illustrates how NFTs could function as digital identities for physical meters, and the role of digital water governance in authorizing token issuance is discussed. These ideas are conceptual rather than operational; they outline how meter-related metadata could become more auditable and interoperable across stakeholders. This paper also proposes a phased pilot pathway as a future validation plan, together with an illustrative evaluation framework to guide pilot design, along with potential security challenges and conceptual mitigation strategies. Moreover, the framework highlights how NFT-enabled identities and smart contracts may support improvements in transparency, accountability, and user trust in SWM systems. It is intended as a foundation for future empirical evaluation in smart-city contexts, not as evidence of a deployed or validated solution.